The CGS often collaborates with local, state, and federal agencies on projects concerning emergency preparedness and community resilience. In this case, we assisted the Colorado Water Conservation Board (CWCB), the Colorado Department of Local Affairs (DOLA), and local governments by providing technical expertise for the Colorado Hazard Mapping Program (CHAMP). The program facilitates effective long-term flood hazard reduction in Colorado. A crucial part of that process is the development of FHZ mapping protocols and debris flow hazard assessments in combination with traditional floodplain mapping. Community engagement and education on the FHZ protocols is ongoing across the state.
The initial impetus for CHAMP was the widespread devastation caused by the catastrophic flooding event along the Front Range in September 2013. Boulder and Larimer counties were the hardest hit, both in mountain communities and areas in the plains downstream. Though not the first time the state has experienced a major flooding event, 2013 galvanized opinions across the state that action had to be taken to recognize and mitigate flooding risks to the residents of the state.
Traditional FEMA Flood Insurance Rate Maps (FIRMs) are elevation-based and delineate only inundation (flooding) hazards. FHZ mapping—accomplished primarily by fluvial geomorphologists—relies on the interpretation of data describing the physical location, form, and active sediment and debris transport processes of a stream or river system. An FHZ map essentially identifies areas where a stream or river might change its path during flooding events. Important basic assumptions regarding an FHZ appraisal are that stream dimensions change during a flood event and that flows are transporting sediment and debris. The unexpected impact of these two processes on the community during a flooding event can be catastrophic and fatal. Fluvial geomorphic hazards exist within all stream corridors of Colorado.
Any regulation based on the Colorado FHZ Delineation Protocol is determined by local communities who are encouraged to explore the development of FHZ maps for the benefit of all residents. Pilot mapping of around 450 miles of stream has already been completed across the state.
[Ed: See the Citations tab below the video for a link/listing of all CHAMP/FHZ publications]
Blazewicz, Michael, Katie Jagt, Joel Sholtes, and Cris Sturm. “Colorado Fluvial Hazard Zone Delineation Protocol v1.0.” Fluvial Hazards. Denver, CO: Department of Natural Resources, Colorado Water Conservation Board, August 2020. https://www.coloradofhz.com/.
Colorado Water Conservation Board. “Fluvial Hazard Zone Fact Sheet v3.4.” Colorado Water Conservation Board, 2020. https://www.coloradofhz.com/.